Skin Flashcards
why do you need to reappl suncreen
P450 enzymes in teh skin can degrade it
clinical manifestation of contact dermatitis
erythema
induration (thick)
scaling
vesiculation
irritant contant dermatitis due to
not immunologic
depends on dose applied
characteristics of irritant contact derm
pink to red patches or plaques
blisters
itching
michenification (epidermal thickening)
allergic contact dermatitis due to
delayed type4 hypersensitivity reaction
first exposure creates antigen on second exposure presents the antigen to t cells that are now sensitized and activates immune response
when does allergic contact dermititis occur
within 12 hr of sensitization
peaks 48-72 hr
contact urticaria due to
IgE mediated
histamine release
presentation of contact urticaria
transient
pruritic
edematous
pink papules or wheals
protective agents from Uv radiation
melanin and amino acids
what is photosensitivity
abnormal sensitivity to UV and visible light due to endogenous or exogenous factors
difference between phototoxicity and photoallergy
toxicity due to activation of certain compounds due to light and can occur at first exposure and allergy is the generation of antigen activation
what is phototxicity
occurs at first exposure
chemicals from meds absorb UV light and reach higher energy excited state
acute phototoxicity reaction
skin red
blister within minutes to hours after light exposure
basically a sunburn
chronic phototoxicity skin reaction
hyperpigmentation - spots
thickening
drugs causing phototoxicity
amiodarone
flouroquinolone
what is photoallergy
type 4 delayed hypersensitivity requires prior sensitization
uv light role in photoallergy
necessary to convert a potential photosensitizing chemical into a hapten that binds to a tissue antigen = allergic response at next exposure
presentation of maculopapular eruptions
morbilliform
start on trunk adn spread to entire body
flat or raised red lesion
symmetrical
itchy macules and papules
small red spots that are itchy and raised
when does maculopapular eruptions occur
appear within first week of therapy
common in amox
clinical presentation or urticaria
pink or red raised papules and plaques
localized vasodilation adn transudation of fluid from small cutaneous blood vessels
angioedema due to vasodilation
large, more red
mechanism of urticaria
type 1 (IgE)
type 3
direct effects on mast cells
inhibition of prostaglandins
fixed drug eruption presentation
bright dusky red
oval or circular patch with central pigmentation
blister
sometimes burning
where do fixed drug eruptions occur
at the same sites on reapeated admin of drug
face hands feet mouth
when does fixed drug eruptions heal
7-20 days after discontinuing
erythema multiforme caused by
type 3 immune reaction
erythema multiforme presents as
red maculae that become edematous and papular
concentric rings of different color : red, purple, white, black
common sites of erythema multiforme
face
hands
limbs
mucous membranes
what is SJS
severe varient of erythema multiforme
SJS presentation
mucosal and conjunctival edema erosions fever myalgia vomiting diarrhea arthralgia skin lesions severe with denudation (detach from body)
complications of SJS
keratitis conjunctival scarring blindness pneumonia dehydration esophagitis
drug causes of SJS
ibuprofen
penicillin
salyicylate
also some genetic predisposition but unclear
severity of TEN
life threatening high mortality rates
clinical manifestations of TEN
prodromal: malaise, sore throat, headache, myalgia, fever, cough
acute onset of cutanoues manifestations within hours or days
macular lesion with burning sensation that enlarges over the body
large blister with redness
detachment of epidermis (necrosis)
areas effected by TENs
palms soles mouth throat nose trachea eyelid cornea conjunctiva
complications of TEN
similar to second degree burns fluid adn electrolyte disorder septicemia pneumonia hepatocellular damage GI ulcer nephritis myocardial damage
mechanism of TEN
cytotoxic intermediates produced during metabolism of carbamaxepine
immunologic
metabolic
what is erythema nodosum
inflammatory reaction of the SC fat
creates dark nodules
presentation of drug induced lupus erythematosus
red rash on face in the form of a butterfly
fever malaise
arthritis
what is purpura
bleeding into the skin
causes of purpura
drugs that interfere with platelet aggregation or coagulation
cytotoxic drugs
direct endothelial damage (bleomycin)
causes of hyperpigmentation
deposit of melanin in the dermis or stimulation of melanin production
amiodarone
oral contraceptive
